The trapezius muscle is a large, triangular muscle that extends from the base of the skull to the lower thoracic spine and across the shoulder blades. It is responsible for moving and stabilizing the shoulder blades and neck, and it also plays a role in maintaining good posture.
The trapezius muscle has three main sections: the upper, middle, and lower trapezius. The upper trapezius is responsible for elevating the shoulder blades and rotating them inward. The middle trapezius helps to retract the shoulder blades and rotate them outward. The lower trapezius helps to depress the shoulder blades and rotate them inward.
Injuries to the trapezius muscle can result from overuse, strain, or trauma. Symptoms of a trapezius muscle injury may include pain, stiffness, and difficulty moving the shoulder blades or neck. Treatment may include rest, physical therapy, and medication.